1. Field of the Invention
The invention generally relates to a solar cell, and more particularly to a solar cell within a preferable internal reflective efficiency.
2. Description of Related Art
A silicon-based solar cell is a typical solar cell adopted commercially. A principle behind the silicon-based solar cell is doping a highly purity semiconductor material (silicon) with a dopant to display different characteristics, so as to form p-type semiconductors and n-type semiconductors, and to attach the p-type and n-type semiconductors with each other to form a p-n junction (interface). When sunlight illuminates a p-n structured semiconductor, energy provided by photons may excite electrons in the semiconductors to generate electron-hole pairs. By configuring electrodes such that holes move towards an electric field direction and electrons move towards an opposite direction (contrary direction) to the electric field direction, a solar cell can be formed. Typically speaking, in order to improve the solar cell, it is pertinent to enhance a photoelectric conversion efficiency of the solar cell.
However, in conventional solar cells, as the thickness of the semiconductor material becomes thinner, a reflective efficiency of the solar cell decreases. In other words, a transmission rate of light passing through the semiconductor material is high, causing a light reusability rate inside the solar cell, or the reflectivity in the solar cell to decrease, and thereby lowering a light absorption rate. Therefore, a photoelectric conversion efficiency of the solar cell is low.